This invention relates to a plug valve assembly for controlling the flow of a high pressure fluid.
Plug valve assemblies are well known in the art and feature a valve member rotatably mounted in a body member and having a through opening which can be positioned relative to two aligned passages in the body member to control the fluid flow through the body member.
Inserts are often provided between the valve member and the corresponding surfaces in the body member to provide an intimate sealing contact with the valve member. These inserts vary in shape and some are provided with tapered outer surfaces while others extend parallel to the corresponding inner surface of the body member. A disadvantage of the tapered inserts is that their sealability is less than optimum since the inserts may preferentially conform to the body member causing a small gap between the mating surfaces of the valve member and the inserts. A disadvantage of inserts with outside diameters parallel to the inside diameter of the plug valve body is that they require the valve assemblies to be disassembled in the event of a leak.